2-acetal-7-ketal-5-norbornene and 2-acetal-7-ketalnorbornane compounds

ABSTRACT

2-Acetal-7-ketal-5-norbornene compounds, such as 2-(1,3dioxolan-2-yl)-3-methyl-7,7-dimethoxy-5-norbornene, and the corresponding norbornane compounds, for example, 2-(1,3-dioxolan2-yl)-3-methyl-7,7-dimethoxynorbornane, are central nervous system depressants; and in addition, the norbornene compounds exhibit anticonvulsant activity. These compounds are synthesized from 1,2,3,4-tetrachloro-5-ketalcyclopentadienes and Alpha ,Bunsaturated aldehydes in a plural step synthesis comprising (1) a Diels-Alder addition, (2) acetalization, (3) dechlorination and, in the case of the norbornane compounds, (4) hydrogenation, as is illustrated by the following equations:

United States Patent [72] Inventor Fredrick Lynn Hamb Rochester, NY.

[2| 1 Appl. No. 765,036

[22] Filed Oct. 4, 1968 [45] Patented Dec. 7, 1971 [73] Assignee EastmanKodak Company Rochester, N.Y.

[ 54] Z-ACETAL-7-KETAL-S-NORBORNENE AND 2- ACETAL-7-KETALNORBORNANECOMPOUNDS l5 Claims, No Drawings {52] [1.8. Cl 260/340.7, 260/338,260/3409, 260/611 R, 424/278, 424/341 [51] Int. Cl ..C07d 13/02, C07d15/04 [50] Field 0! Search 260/3409, 340.7, 338, 61 l PrimaryExaminerAlton D. Rollins Assistant Examiner.lames H. TurnipseedAnomeysW. H. J. Kline and W. E. Neely ABSTRACT:2-Acetal-7-ketal-5-norbornene compounds,

such as 2-( l,3-dioxolan-2yl)-3-methyl-7,7-dimethoxy-5-norbornene, andthe corresponding norbornane compounds, for example, 2-( l,3-dioxolan-2-yl)-3-methyl-7,7-dimethoxynorbornane, are central nervoussystem depressants; and in addition, the norborncne compounds exhibitanticonvulsant activity. These compounds are synthesized from 1,2,33,4-tetrachloro-S-ketalcyclopentadienes and a,B-unsaturated aldehydes in aplural step synthesis comprising l a Diels-Alder addition, (2)acetalization, (3) dechlorination and, in the case of the norbornanecompounds, (4) hydrogenation, as is illustrated by the followingequations:

OCH; CIIO OCH3 OCH OCHa

OCH 0CH 2-ACETAlL-7-KETAL-5-NORBORNENE AND 2-ACE'IIAL- 7-KETALNORBORNANECOMPOUNDS This invention relates to novel 2-acetal-7-ketal-5-norborneneand 2-acetal-7-ketalnorbornane compounds having useful pharmacologicalactivity. These compounds may be represented by the general formula:

Ra OR i134 \ORG wherein each of R, R R and R individually represents alower alkyl group, each of R and R represents hydrogen or a lower alkylgroup, wherein R and R when taken collectively represent anunsubstituted polymethylene radical having 2 to 4 carbon atoms or apolymethylene radical having 2 to 4 carbon atoms which is substitutedwith a lower alkyl group or a lower alkoxyalkyl group, wherein R and Rwhen taken collectively represent an unsubstituted polymethylene radicalhaving 2 to 4 carbon atoms or a polymethylene radical having 2 to 4carbon atoms which is substituted with a lower alkyl group or a loweralkoxyalkyl group and A represents an ethylene radical or a vinyleneradical.

By the ten-n lower alkyl group" is meant an alkyl group having 1 to 6carbon atoms, whether branched or straight chain, such as methyl, ethyl,propyl, isopropyl, butyl, tert-butyl, pentyl and hexyl, for example.

By the term lower alkoxyalkyl group" is meant an alkoxyalkyl grouphaving 2 to 6 carbon atoms, whether branched or straight chain, such asmethoxymethyl, Z-methoxyethyl, 2- ethoxyethyl, 2-propoxyethyl,2-butoxyethyl, 3-propoxypropyl, 3-isopropoxypropyl and2-isopropoxypropyl, for example.

Preferred alkyl and alkoxyalkyl groups are straight chain groups, withthe methyl and methoxymethyl groups being particularly preferred. Thepolymethylene groups represented by R and R, collectively, and R and R,collectively, are preferably unsubstituted. Preferably, R and Rindividually are the same lower alkyl group. Similarly, R" and R,individually, preferably are the same lower alkyl group.

Illustrative of the compounds having the formula I are:

Z-(dimethoxymethyl)-7,7-dimethoxy-5-norbornene,

2-(dimethoxymethyl-7,7-diethoxy-5-norbornene,

2-(dimethoxymethyl)-7,7-dihexoxy-5-norbornene,

Z-(dihexoxymethyl)-7,7-dimethoxy-5-norbornene,

2-(dihexoxymethyl)-7,7-dihexoxy-5-norbornene,

2-(dimethoxymethyl)-2-methyl-7,7 dimethoxy-5-norbornene,

2-(dimethoxymethyl)-2-hexyl-7,7-dimethoxy-5-norbor nene,

Z-(dimethoxymethyl)-3-hexyl-7,7-dimethoxy-5-norbornene,

2-( 2-dioxolanyl )-7 ,7-dimethoxy-5 -norbornene,

2-( 2-dioxolanyl )-7,7-ethylenedioxy5-norbomene,

2-[ 2-( l,3-dioxepanyl ]-7,7-tetramethylenedioxy-S-norbornene,

2-(dimethoxymethyl)-7,7-dimethoxynorbomane,

2-(dimethoxymethyl)- 7,7-diethoxynorbornane,

2-(dimethoxymethyl)-7,7-dihexoxynorbomane,2-(dihexoxymethyl)-7,7-dimethoxynorbomane,2(dihexoxymethyl)-7,7-dihexoxynorbornane,

Z-(dimethoxymethyl)-2-methyl-7,7-dimethoxynorbornane,

Z-(dimethoxymethyl)-2-hexyl-7,7-dimethoxynorbornane,

Z-(dimethoxymethyl)-3-hexyl-7,7-climethoxynorbornane,

2-( 2-dioxolanyl )-7,7-dimethoxynorbomane,

2-( 2-dioxolanyl )-7,7-ethylenedioxynorbornane, and

2-[2-( l,3-dioxepanyl)]-7,7-tetramethylenedioxynorbornane, for example.

The compounds of this invention are readily obtained by a plural stepsynthesis from known starting materials, viz,l,2,3,4-tetrachloro-5-ketalcyclopentadienes, a, B-unsaturated aldehydesand monohydric or dihydric alcohols.

The first step of this synthesis comprises a Diels-Alder addition of al,2,3,4-tetrachloro-5-ketalcyclopentadiene with an a, B-unsaturatedaldehyde, as illustrated by the equation:

The reaction conditions of the Diels-Alder addition reaction are notcritical, but normally the l,2,3,4-tetrachloro-5ketalcyclopentadiene andthe a, B-unsaturated aldehyde are charged to a suitable reaction vesselin approximately equimolar amounts and heated at elevated temperature,generally from about 50 to about I50 C. Temperatures above C. areordinarily preferred. The reaction can be carried out in the presence ofan inert solvent, if desired, but ordinarily the use of a solvent isunnecessary. Solvents that can be employed include, for example,aromatic hydrocarbons (e.g., benzene, toluene and xylene),cycloaliphatic hydrocarbons (e.g., cyclohexane) or chlorinatedhydrocarbons (e.g., chlorobenzene, Cl CI-ICI-ICI and ClCH CCl Thesolvents named are intended to be illustrative and not limitative of theinvention. Other inert solvents having an appropriate boiling pointcould be used.

The aldehyde product obtained from the Diels-Alder addition reaction isreacted with a monohydric or dihydric alcohol to convert the aldehyde tothe corresponding acetal. Illustrative alcohols include, for example,methanol, ethanol, propanol, isopropanol, butanol, tertiary butanol,ethylene glycol, propylene glycol (1,2-propanediol), l,3propanediol, l,4-butanediol, 3-methoxyl ,2-propanediol and monoacetin.

The ratio of alcohol to aldehyde is not critical, although a ratio of 2equivalents of alcohol to one equivalent of aldehyde, i.e., 2 moles of amonohydric alcohol or 1 mole of a dihydric alcohol per mole of aldehyde,is normally employed.

This reaction (acetalization) is catalyzed by acid, such as organiccarboxylic or sulfonic acids or mineral acids. Preferred are the organicacids such as: benzenesulfonic acid, p-toluenesulfonic acid and thelike.

To ensure carrying the reaction to completion, the water formed shouldbe continuously removed. This can be effected ,in any suitable manner. Aconvenient technique comprises 1' conducting the reaction under refluxin the presence of a solvent, such as benzene, which forms a minimumboiling azeotrope with water, while separating water from thedistillate.

The tetrachloro-Z-acetal-7-ketal which is produced in this step has theformula:

wherein R, R', R, R, R and R have the meaning previously assigned tothem.

The reaction is normally effected at elevated temperature, with refluxtemperatures being convenient.

The norbomane compounds of the invention and which have the formula:

(VII) x o R wherein R, R, R, R, R and R have the meaning previouslyassigned to them are prepared by hydrogenating the norbornene compoundshaving the formula Vl.

The hydrogenation is generally effected at moderately elevatedpressures, e.g. about 25 to 100 p.s.i., and autogeneous temperaturesover a suitable catalyst. Particularly preferred catalysts are the noblemetal oxides such as platinum or palladium oxide, although othercatalysts such as Raney nickel and the like may be employed. Thehydrogenation is desirably effected in the presence of an inert solvent,especially a lower alkanol such as methanol, ethanol, propanol,isopropanol, butanol and the like.

The norbornene and norbornane compounds of this invention are centralnervous system depressants, and in addition, the norbornene compoundsexhibit anticonvulsant activity. When employed for these purposes, thecompound is administered to a mammal in an efi'ective amount. The actualamount is not critical, and will vary with the subject and the dosagenecessary in a particular case. In general, however, effective amountsas depressants and anticonvulsants are in the range of from about to 500milligrams per kilogram of mammal body weight, although higher and lowerdosage levels may be employed if desired.

The mode of administration is not critical, and the compound may beadministered by enteric or parenteral methods. The form of the compoundis likewise not critical, and it may be in the form of tablets,capsules, oral or injectable solutions or suspensions, suppositories andthe like, containing the compound, in admixture with pharmaceuticallyacceptable excipients.

The following examples are illustrative. Infrared spectra of theproducts were consistent with their assigned structures.

EXAMPLE I 105 Grams of crotonaldehyde were added to 396 grams ofdimethoxy-S-norbornene boiling at 100 C./0.0l mm. and having an index ofrefraction, ri of l.5270 were obtained. The 2,4-dinitrophenylhydrazonederivative was prepared and melted at l58-l 60 C.

c H Cl N Calculated for c.,1-1...c1..N.o.: 39.7% 3.1% 27.6% 10.9% Found:39.5% 2.9% 27.6% 10.8%

EXAMPLE 2 Employing procedures similar to those described in example lexcept that acrolein was substituted for crotonaldehyde, there wasobtained an 87 percent yield of l,4,5,6-tetrachloro-2-formyl-7,7-dimethoxy-5-norbornene, b.p. l l3 C./0.25 mm.;n,," 1.5296.

EXAMPLE 3 Employing procedures similar to those described in example 1,except that methacrolein was substituted for crotonaldehyde, there wasobtained a 57 percent yield of 1,4,5,6-tetrachloro-2-formyl-2-methyl-7,7-dimethoxy-S-norbomene, b.p. l1lC./0.009 mm.; m,=1.5260. lts 2,4-dinitrophenylhydrazone derivativemelted at l56-l58 C.

c H Cl N Calculated forC, l-l Cl4N,O6: 39.7% 3.1% 27.6% 10.9% Found:40.0% 3.4% 27.4% 10.6%

EXAMPLE 4 Employing procedures similar to those described in example 1,except that l,2,3,4-tetrachloro-5,S-ethylenedioxycyclopentadiene wassubstituted for the tetrachlorodimethoxycyclopentadiene, there wasobtained a 53 percent yield of1,4,5,6-tetrachloro-2-formyl-3-methyl-7,7ethylenedioxy-5- norbornene,b.p. 147 C./0.003 mm.; n 1.5372. lts 2,4- dinitrophenylhydrazonederivative melted at 227-230 C.

C H Cl N Calculated for CI1HHCI4N40H: 39.9% 2.8% 27.7% 10.9% Found:40.0% 2.6% 28.0% 10.6%

EXAMPLE 5 EXAMPLE 6 A solution of 237 grams of the aldehyde of example 1in 600 milliliters of benzene was admixed with 44 grams of ethyleneglycol of 2 grams of p-toluenesulfonic acid. The resulting solution wasrefluxed for 18 hours, during which time the water 5 formed wasseparated by a Dean-Stark trap. After the additionl,2,3,4-tetrachloro-5,5-dimethoxycyclopentadiene and the resultingsolution was gently refluxed for 24 hours. On rectification of theresulting viscous reaction mixture 320 grams (64 percent yield) ofl,4,5,-tetrachloro-2-formyl-3-methyl-7.7-

C H Cl Calculated for C HmChQ: 4l.3% 4.3% 37.5% Found: 41.0% 41% 37.8%

EXAMPLE 7 C H C1 Calculated for C H ChQu 42.9% 4.6% 36.2% Found: 42.9%4.7% 36.6%

EXAMPLE 8 c n Cl Calculated for cmnwctosz 42.7% 4.8% 33.6% Found: 42.6%5.1% 53.9%

EXAMPLE 9 Employing procedures similar to those described in example 6,except that the product of example 2 was substituted for that of example1, there was obtained a 77 percent yield of1,4,5,6-tetrachloro-2-(2-dioxolanyl)-7,7-dimethoxy-5-norbornene, b.p. 80C./0.002 mms, n 1.5295.

C H Cl Calculated for C1 H14Cl4O4: 39.6% 3.9% 39.0% Found: 39.3% 3.6%39.2%

EXAMPLE Employing procedures similar to those described in example 6,except that the product of example 3 was substituted for that of example1, there was obtained a 79 percent yield ofl,4,5,6-tetrachloro-2-(2-di0xolanyl)-2-methyl-7,7-dimethoxy-S-norbornene,b.p. 88C./0.004 mm.; r1 1.5300.

Calculated for C H CLO4: 41.5% 3.8% 37.7% Found: 41.7% 3.7% 37.8%

EXAMPLE l3 Employing procedures similar to those described in example 6,except that the product of example 5 was substituted for that of example1, there was obtained a 44 percent yield of l,4,5,6-tetrachloro-2-(2-dioxolanyl )-3-methyl-7,7-dibutoxy-5 -norbomene, b.p. 89 C./0.00l mm.;n 1.5088.

C H Cl Calculated for C H ChO z 49.4% 6.1% 30.7% Found: 49.2% 6.2% 30.3%

EXAMPLE 14 To a solution of 1 13.4 grams of the product of example 6 in1,000 ml. of tetrahydrofuran and 266 grams of tert-butanol was added 100grams of finely chopped sodium. The resulting mixture was stirredvigorously while gently refluxing in a nitrogen atmosphere for 7 hours.At the end of this time the excess sodium was eliminated by the cautiousaddition of 700 ml. of methanol. The reaction mixture was then pouredinto two liters of ice and extracted with four 500 ml. portions ofether. The combined ether extracts were washed twice using a 1,000 ml.portion of water saturated with sodium chloride each time, and thendried over anhydrous magnesium sulfate. After filtration and thenevaporation there remained an oil which on distillation yielded 55.4grams (77 percent yield) of2-(2-dioxolanyl)-3-methyl-7,7-dimethoxy-5-norbornene, b.p. 100-103C./0.5-0.6 mm.; n 1.4821.

Calculated for C H O 65.0% 8. 4% Found: 65.1% 8.3%

EXAMPLE l5 c H Cl r a for C,.H.,0.; 66.1% 8.7% Calculate for C H ChQg41.3% 4.3% 315% Fuufldi 651% 33% Found: 41.1% 4.2% 37.3%

7 EXAMPLE l6 EXAMPLE H Employing procedures similar to those describedin exam- C H Cl Calculated for c,,n,.ci.0.= 41.2% 4.5% 37.4% Found:40.9% 4.8% 37.4%

EXAMPLE 12 Employing procedures similar to those described in example 6,except that the product of example 4 was substituted for that of example1, there was obtained a 79 percent yield of 1,4,5,6-tetrachloro-2-(2-dioxolanyl )-3-methyl-7,7-ethylenedioxy-S-norbornene, b.p. 90 C./0.003 mm; n

ple 14, the product of Example 8 was converted to 2-[2-(4-methoxymethyldioxolanyl ]-3-methyl-7,7-dimethoxy-5-norbornene, b.p.1l7-37 C./0.1-0.2 mm..; n 1.4773. A yield of percent was obtained.

Calculated for C H O 63.4% 8.5% Found: 63.1% 8.4%

EXAMPLE 17 Employing procedures similar to those described in example14, the product of example 9 was converted to2-(2-dioxolanyl)-7,7-dimethoxy-5-norbornene, b.p. 88-102 C./0.1-0 .3mm.; n 1.4832. A yield of 68 percent was obtained.

Calculated for C,,H,,,O.: 63.7% 8.0%

Found: 63.5% 7.9%

EXAMPLE l8 Employing procedures similar to those described in example14, the product of example 10 was converted to2-(2-dioxolanyl)-2-methyl-7,7-dimethoxy-5-norbomene, b.p. 88-98C./0.l-.2 mm.; n 1.4846. A yield of 66 percent was obtained.

Calculated for c,,u,.,o,: 65.0% 8.4% Found: 64.7% 8.4%

EXAMPLE l9 Employing procedures similar to those described in example14, the product of example 1 l was converted to 2-methyl-2-(dimethoxymethyl)-7,7-dimethoxy-5-norbomene, b.p. 100 C./l mm.;n1.5474.

Calculated for c,,|-i,,0,; 64.5% 9.1% Found: 64.6% 9.1%

EXAMPLE Employing procedures similar to those described in example 14,the product of example 12 was converted to 2-(2-diox- Employingprocedures similar to those described in example 14, the product ofexample 13 was converted to 2-(2-dioxolanyl)-3-methyl-7,7-dibutoxy-5-norbomene, b.p. 92-102 C./O.2 mm.;'1 1.4852.

Calculated for C,,,H ,O,: 70.3% 99% Found: 69.9% 9.9%

EXAMPLE 22 A mixture of 0.2 grams of platinum oxide and a solution of 24grams of the 2-(2-dioxolanyl)-3-methyl-7,7-dimethoxy-5- norborneneproduced as described in example 14 in 125 milliliters of ethanol wassubjected, with shaking, to a pressure of 60 pounds of hydrogen in amedium-pressure hydrogenation apparatus. After cessation of hydrogenuptake, the reaction mixture was filtered. The filtrate was evaporatedon a steam bath and the residual liquor was distilled to yield 19.4grams of 2-(2-dioxolanyl)-3-methyl-7,7-dimethoxynorbornane, b.p.95-l05bL C./0.1-0.2 mm.; n 1.4780.

Calculated for C H O 64.4% 9.2% Found: 64.7% 9.1%

Employing procedures similar to those described in example 22 the5-norbornene compounds of examples l5, 1 6,17, 1 8,1920 and 21 can beconverted to 2-[2-( 1,3-dioxanyl)]-3-methyl-7,7-dimethoxynorbomane,2-[2-(4'-methoxymethyldioxolanyl)]-3-methyl-7,7-dimethoxynorbornane, 2-

(2-dioxolanyl)-7,7-dimethoxynorbornane, 2-(2-dioxolanyl)-2-methyl-7,7-dimethoxynorbornane, 2-methyl-2(dimethoxymethyl)-7,7-dimethoxynorbornane, 2-( 2-dioxolanyl )-3methyl-7,7-ethylenedioxynorbornane and 2-( 2-dioxolanyl )-3-methyl7,7-dibutoxynorbornane, respectively.

Each of the compounds of examples 14-20 and 22 was evaluatedsimultaneously for central nervous system depressant activity andtoxicity by the following procedure:

An aqueous emulsion containing 100 milligrams of the compound to betested and 1 drop of Tween (a nonionic surfactant marketed by AtlasPowder Co.) per milliliter of emulsion was prepared. The emulsion wasthen administered intraperitoneally to each of 10 mice weighing 20 to 30grams in an amount of 1,000 milligrams of the drug per kilogram of bodyweight. The test animals were then observed for the first 6 hours aftertreatment for central nervous system depressant effects and then at 24and 48 hours of mortality. If all or most of the mice die, subsequenttests are carried out wherein the dosage is reduced by halves until alow dose of 125 mg./kg. is given. After 48 hours the median lethal doseis bracketed and approximated (ALD For example, if all animals die at1,000 mg./kg. and none die at 500 mg./kg., the ALD is 750 mg./kg.

All the compounds tested were found to be Class lV depressants. That is,the animals exhibited reduced activity, ataxia, and loss of the rightingreflex when placed upon their backs. The products ofexamples 16, l7, l9and 20 exhibited no toxic effects at a dosage of 1,000 mg./kg. and theproduct of example l4 exhibited no toxic effects at a dosage of 500mg./kg. The products of examples 15, 18 and 22 had ALD values of 750mg./kg.

No toxic effects were observed when the test emulsions were administeredorally to mice at a level of 2,000 mg./kg.

The compounds of examples 14-20 and 22 were also evaluated foranticonvulsant activity by the following procedure:

Each of 10 male mice weighing 20-25 grams was treated orally with anaqueous emulsion of the compound to be evaluated and then, 10 minutesbefore the anticipated time of peak anticonvulsant activity, was treatedsubcutaneously with milligrams of a 5 percent Metrazol solution perkilogram of animal body weight. The animals were observed for the next60 minutes for the occurrence of seizures. Transient intermittent jerksor tremulousners were not considered as being convulsions. Absence ofeven a threshold convulsion (one episode of clonic spasms persisting forat least 5 seconds) was taken as the endpoint of the test. Variousdosages were administered and the dosage which effectively preventedMetrazol-induced convulsions in 50 percent of the animals (ED wasestimated.

These results are summarized as follows:

Example ED mgJkg.

In this test mgjkg. ol'the Metrazol solution was administered.

' No anticonvulsant effects were observed at these dosages.

[t is here noted that for purposes of classification four centralnervous system depressant classes were established as follows:

Class 1 The activity of the test animals decreases.

Class 2 Class lplus ataxia (incoordinated muscular activity orstaggering),

Class 3 Class 1 plus Class 2 plus delayed righting reflex (the abilityof the animal to right itself when placed on its back).

Class 4 Class 1 plus Class 2 plus Class 3 plus loss of righting reflex.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention as described hereinbefore and as defined in the appendedclaims.

l claim:

l. A compound having the formula:

wherein each of R, R, R and R individually represents lower alkyl, eachof R and R represents hydrogen or lower alkyl, wherein R and R whentaken collectively represent unsubstituted polymethylene having two tofour carbon atoms, wherein R and R when taken collectively representunsubstituted polymethylene having two to four carbon atoms and Arepresents ethylene or a vinylene.

2. A compound in accordance with claim ll wherein R and R when takenindividually are the same and represent lower alkyl and when takencollectively represent unsubstituted polymethylene having two to fourcarbon atoms and wherein R and R when taken individually are the sameand represent lower alkyl and when taken collectively representunsubstituted polymethylene having two to four carbon atoms.

3. A compound in accordance with claim 1 wherein A represents vinylene.

4. A compound in accordance with claim 1 wherein A represents ethylene.

5. A compound in accordance with claim 1 wherein A represents vinyleneand each of R and R is methyl.

6. A compound in accordance with claim ll wherein A represents vinylene,each of R and R is methyl, each of R and R represents hydrogen or loweralkyl and wherein R and R are to be taken collectively and representunsubstituted polymethylene having two to four carbon atoms.

7. A compound in accordance with claim l wherein said compound is 2-(2-dioxolanyl)-7,7-dimethoxy-5-norbornene.

8. A compound in accordance with claim ll wherein said compound is2-(2-dioxolanyl)-2-methyl-7,7-dimethoxy-5-norbornene.

9. A compound in accordance with claim ll wherein said compound is 2-(2-dioxolanyl)-3-methyl-7,7-dimethoxy-5-nor bornene.

10. A compound in accordance with claim 1 wherein said compound is2-[2-( l,3-dioxanyl)]-3-methyl-7,7-dimethoxy-5- norbornene.

11. A compound in accordance with claim l wherein said compound is2-[2-(4-methoxymethyldioxolanyl)]-3-methyl- 7,7-dimethoxy-5-norbornene.

12. A compound in accordance with claim ll wherein said compound isZ-(dimethoxymethyl)-2-methyl-7,7-dimethoxy- 5norbornene.

13. A compound in accordance with claim 1 wherein said compound is2-(2-dioxolanyl)-3-methyl-7,7-dibutoxy-5-norbornene.

114. A compound in accordance with claim 1 wherein said compound is2-(2-dioxolanyl)-3-methyl-7,7-ethylenedioxy-5' norbornene.

115. A compound in accordance with claim 1 wherein said compound isZ-(Z-dioxolanyl)-3-methyl-7,7-dimethoxynorbornane.

2. A compound in accordance with claim 1 wherein R1 and R2 when takenindividually are the same and represent lower alkyl and when takencollectively represent unsubstituted polymethylene having two to fourcarbon atoms and wherein R5 and R6 when taken individually are the sameand represent lower alkyl and when taken collectively representunsubstituted polymethylene having two to four carbon atoms.
 3. Acompound in accordance with claim 1 wherein A represents vinylene.
 4. Acompound in accordance with claim 1 wherein A represents ethylene.
 5. Acompound in accordance with claim 1 wherein A represents vinylene andeach of R1 and R2 is methyl.
 6. A compound in accordance with claim 1wherein A represents vinylene, each of R1 and R2 is methyl, each of R3and R4 represents hydrogen or lower alkyl and wherein R5 and R6 are tobe taken collectively and represent unsubstituted polymethylene havingtwo to four carbon atoms.
 7. A compound in accordance with claim 1wherein said compound is 2-(2-dioxolanyl)-7,7-dimethoxy-5-norbornene. 8.A compound in accordance with claim 1 wherein said compound is2-(2-dioxolanyl)-2-methyl-7,7-dimethoxy-5-norbornene.
 9. A compound inaccordance with claim 1 wherein said compound is2-(2-dioxolanyl)-3-methyl-7,7-dimethoxy-5-norbornene.
 10. A compound inaccordance with claim 1 wherein said compound is2-(2-(1,3-dioxanyl))-3-methyl-7,7-dimethoxy-5-norbornene.
 11. A compoundin accordance with claim 1 wherein said compound is2-(2-(4-methoxymethyldioxolanyl))-3-methyl-7,7-dimethoxy-5-norbornene.12. A compound in accordance with claim 1 wherein said compound is2-(dimethoxymethyl)-2-methyl-7,7-dimethoxy-5-norbornene.
 13. A compoundin accordance with claim 1 wherein said compound is2-(2-dioxolanyl)-3-methyl-7,7-dibutoxy-5-norbornene.
 14. A compound inaccordance with claim 1 wherein said compound is2-(2-dioxolanyl)-3-methyl-7,7-ethylenedioxy-5-norbornene.
 15. A compoundin accordance with claim 1 wherein said compound is2-(2-dioxolanyl)-3-methyl-7,7-dimethoxynorbornane.